KR100687159B1 - Solid Electrolyte Battery - Google Patents

Abstract

The present invention includes a positive electrode, a negative electrode disposed to face the positive electrode, a separator disposed between the positive electrode and the negative electrode, and a solid electrolyte respectively present between the positive electrode and the separator and the separator and the negative electrode, the separator having a thickness of 5 ㎛ to 15 When the solid electrolyte cell is made of a polyolefin porous membrane having a porosity range of 25% to 60% and the temperature of the solid electrolyte cell is in the range of 100 ° C to 160 ° C, the impedance of the solid electrolyte cell is higher than that at room temperature, and the energy The present invention relates to a solid electrolyte cell having improved density and safety.

Solid Electrolyte Battery, Separator, Porosity, Impedance

Description

Solid Electrolyte Battery

1 is a perspective view showing a structural example of a solid electrolyte battery according to the present invention.

FIG. 2 is a cross-sectional view taken along the line X-Y of FIG. 1.

3 is a perspective view showing a state in which the anode and the cathode are formed of a wound electrode.

4 is a perspective view showing a structural example of an anode.

5 is a perspective view showing a structural example of a negative electrode.

6 is a photograph showing a fibril structure of a separator according to the present invention.

7 is a perspective view showing a structural example of a solid electrolyte battery according to the present invention.

FIG. 8 is a cross-sectional view taken along the line X-Y of FIG. 7.

9 is a perspective view showing a state in which the anode and the cathode are formed of a wound electrode.

10 is a perspective view showing a structural example of an anode.

11 is a perspective view showing a structural example of a negative electrode.

12 is a cross-sectional view showing an example of a separator according to the present invention.

It is a schematic diagram which shows the relationship between a separator and electrode width.

It is sectional drawing which shows the structural example of an exterior film.

15 is a graph showing a relationship between a temperature of a battery and internal battery impedance according to Example 1. FIG.

16 is a graph showing a relationship between a temperature of a battery and internal battery impedance according to Example 6. FIG.

17 is a graph showing the relationship between the breaking strength and the breaking elongation of the separator of each battery according to Examples 1 to 7. FIG.

18 is a photograph showing a fibrillated structure of a separator of a battery according to Example 6. FIG.

<Explanation of symbols for the main parts of the drawings>

1, 20: gel electrolyte cell 2, 21: positive electrode

2a: positive electrode active material layer 3a: negative electrode active material layer

2b: positive electrode current collector 3b: negative electrode current collector

3, 22: cathode 4, 23: gel electrolyte layer

5, 24: separator 6, 25: winding electrode

7, 26: exterior film 8, 27: positive terminal

9, 28: negative electrode terminal 10, 29: resin film

The present invention relates to solid electrolyte cells using solid electrolytes, and more particularly to solid electrolyte cells with significantly improved energy density and safety using separators having specific mechanical strength and thermal properties.

Batteries are an important element as a power source of many portable electronic devices such as mobile phones and notebook personal computers. In order to reduce the size and weight of electronic devices, large-capacity and small batteries have been required. From this point of view, lithium batteries with high energy density and output density are suitable for use as a power source of portable electronic devices. The average discharge voltage of the lithium secondary battery in which the carbon material is used for the negative electrode is 3.7 V or more. Deterioration resulting from charge and discharge can also be prevented relatively satisfactorily. Thus, lithium batteries have the advantage that a high energy density can be easily realized.

Lithium batteries are required to be manufactured in various types of types of batteries of high flexibility and degrees of freedom, thin and large area sheet batteries, and thin and small area card batteries. Conventional structures in which battery elements and electrolytes, which are positive and negative electrodes, are encapsulated in metal cans may be difficult to manufacture in various forms. When using electrolyte solution, a manufacturing process becomes overly complicated. In addition, there should be measures against leakage of electrolyte.

In order to solve the problems of the above process, research and development have been carried out for a battery using a solid electrolyte using an organic polymer or inorganic ceramic having conductivity and a gel solid electrolyte (so-called "gel electrolyte") impregnated with a matrix polymer with an electrolyte solution. Have been. Solid electrolyte cells and gel electrolyte cells using a solid electrolyte include an immobilized electrolyte. Therefore, since the contact between the electrode and the electrolyte can be maintained, the battery does not need to encapsulate the electrolyte by using a metal can or by applying pressure to the battery element. Film facing materials can be used to reduce the thickness of the cell. Therefore, a battery having a higher energy density than the conventional battery can be obtained.

 In general, the solid electrolyte of the solid electrolyte cell has a suitable mechanical strength as disclosed in MATERIAL TECHNIQUE OF HIGH-PERFORMANCE SECONDARY BATTERY AND EVALUATION, APPLICATION AND DEVELOPMENT OF THE SAME (Technical Information Association, 1998). Therefore, a battery structure different from the conventional battery using the electrolyte solution can be selected. For example, it has been reported that no separator is required between the anode and the cathode. This fact is known as an advantage of the solid electrolyte.

The reported solid electrolytes suffer from unsatisfactory strength, including puncture resistance, when compared to conventional separators including polyolefin microporous membranes and the like. In the case where the thickness of a battery using a conventional solid electrolyte is reduced to, for example, 40 μm or less to increase the energy density, a problem arises that an internal short circuit often occurs after the battery is manufactured by an assembly process. As above, the energy density of the solid electrolyte cell cannot be easily increased by reducing the thickness of the solid electrolyte layer.

In the case of heat resistance, which is an index for evaluating the reliability of the battery, the heat resistance of the conventional solid electrolyte battery is unsatisfactory. Some of the commercial batteries are tuned to use the so-called "shutdown effect" to improve heat resistance. On the other hand, no solid electrolyte material for a solid electrolyte battery having a shutdown effect was found.

In terms of reliability and safety of the battery, the reliability and safety cannot be easily achieved as the density of the battery increases, so a technique for maintaining the safety of the solid electrolyte cell should also be considered when designed to increase the energy density of the solid electrolyte cell.

Thin cells include a separator made of polyolefin. In particular, a polyethylene separator is used.

Under normal conditions, the battery temperature melts down, no short circuit occurs between the positive electrode and the negative electrode, and no thermal runaway occurs. When the battery is used under an abnormal environment, for example, when the battery is charged at a higher voltage, an accident may occur as the temperature of the battery increases. In such a case, using a separator made of polyethylene having a lower meltdown temperature than polypropylene may cause the meltdown of the separator. In other words, leakage of the separator occurs, causing internal short circuit between the positive electrode and the negative electrode. In other words, the battery may generate heat.

It is an object of the present invention to provide a solid electrolyte cell of high energy density with improved safety.

In order to achieve the object of the present invention, in accordance with an aspect of the present invention, a positive electrode, a negative electrode disposed to face the positive electrode, a separator disposed between the positive electrode and the negative electrode, and a solid existing between the positive electrode and the separator and the separator and the negative electrode, respectively An electrolyte, wherein the separator is made of a polyolefin porous membrane having a thickness in the range of 5 μm to 15 μm and a porosity in the range of 25% to 60%, and the solid electrolyte when the temperature of the solid electrolyte cell is in the range of 100 ° C. to 160 ° C. A solid electrolyte battery is provided, wherein the battery has a higher impedance than at room temperature.

The solid electrolyte cell according to the present invention comprises a separator composed of a polyolefin porous membrane having specific thickness, porosity and thermal properties. Thus, energy density can be increased and safety can be improved.

According to still another aspect of the present invention, a separator includes a positive electrode, a negative electrode disposed to face the positive electrode, a separator disposed between the positive electrode and the negative electrode, and a solid electrolyte respectively present between the positive electrode and the separator and between the separator and the negative electrode. Is a polyolefin porous membrane having a thickness in the range of 5 μm to 15 μm, porosity in the range of 25% to 60%, a breaking strength of less than 1650 kg / cm 2, and an elongation at break of 135% or more. A battery is provided.

The solid electrolyte cell according to the present invention comprises a separator composed of a polyolefin porous membrane having specific thickness, porosity and thermal properties. Thus, energy density can be increased and safety can be improved.

According to another aspect of the invention, the separator comprises a positive electrode, a negative electrode disposed to face the positive electrode, a separator disposed between the positive electrode and the negative electrode, and a solid electrolyte respectively between the positive electrode and the separator and between the separator and the negative electrode, the separator Is made of a composite material of polyethylene and polypropylene, the thickness of this polyolefin porous membrane is in the range of 5 μm to 15 μm, the shutdown temperature is substantially the same as the shutdown temperature of the separator made of polyethylene, and the meltdown temperature is polypropylene. There is provided a solid electrolyte battery, characterized in that 10 to 30 ℃ higher than the meltdown temperature of the separator produced.

The solid electrolyte cell according to the present invention includes a separator composed of a composite material of polyethylene and polypropylene. Thus, energy density can be increased and safety can be improved.

According to another aspect of the invention, the separator comprises a positive electrode, a negative electrode disposed to face the positive electrode, a separator disposed between the positive electrode and the negative electrode, and a solid electrolyte disposed between the positive electrode and the separator and between the separator and the negative electrode, respectively Is formed by adhering a first separator made of polyethylene and a second separator made of polypropylene to each other, the thickness of the separator is in the range of 5 μm to 15 μm, and the shutdown temperature is substantially the same as the shutdown temperature of the separator made of polyethylene. The same, the meltdown temperature is provided, the solid electrolyte cell, characterized in that the meltdown temperature of the separator made of polypropylene is substantially the same.

The solid electrolyte battery according to the present invention includes a separator formed by adhering a first separator made of polyethylene and a second separator made of polypropylene to each other. Thus, energy density can be increased and safety can be improved.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments described in conjunction with the accompanying drawings.

<Detailed Description of the Preferred Embodiments>

<First Embodiment>

Embodiments of the present invention are described below.                     

Structure examples of the gel electrolyte cell 1 according to the present embodiment are shown in Figs. 1 and 2. The gel electrolyte cell 1 comprises a stripe positive electrode 2, a stripe electrode 3 formed on top of each of the stripe negative electrode 3, the positive electrode 2 and the negative electrode 3 disposed so as to face the positive electrode 2, And a separator 5 in which a gel electrolyte layer 4 is disposed between each of the positive electrode 2 and the negative electrode 3 formed thereon.

The gel electrolyte battery 1 is a structure in which the separator 5 is laminated between the positive electrode 2 and the negative electrode 3 on which the gel electrolyte layer 4 is formed. In addition, the wound electrode 6 shown in FIG. 3 is formed by winding the anode 2 and the cathode 3 in the longitudinal direction. The wound electrode 6 is hermetically sealed with an outer film 7. The positive terminal 8 is connected to the positive electrode 2, while the negative terminal 9 is connected to the negative electrode 3 with each other. The positive terminal 8 and the negative terminal 9 are inserted into a seal which is the circumference of the outer film 7. Each portion where the positive terminal 8 and the negative terminal 9 are in contact with the exterior film 7 is provided with a resin film 10.

As shown in Fig. 4, the positive electrode 2 includes a positive electrode active material layer 2a formed on each of both sides of the positive electrode current collector 2b and containing a positive electrode active material. The positive electrode current collector 2b is made of metal foil such as aluminum foil, for example.

The positive electrode active material may be a lithium composite oxide such as lithium cobalt acid, lithium nickelate or lithium spinel manganate. The lithium composite oxide may be used alone or in plural kinds of the above materials.

The average particle size of the lithium composite oxide is preferably 15 μm or less. When a lithium composite oxide having an average particle size of 15 µm or less is used as the positive electrode active material, a gel electrolyte battery having a low internal resistance and excellent output characteristics can be obtained.

4 shows a state in which the gel electrolyte layer 4 to be described later is formed on the positive electrode active material layer 2a of the positive electrode 2.

As shown in Fig. 5, the negative electrode 3 contains a negative electrode active material and includes a negative electrode active material layer 3a formed on each of both surfaces of the negative electrode current collector 3b. The negative electrode current collector 3b is made of metal foil such as copper foil.

The negative electrode active material can be a material that can be doped / dedoped with lithium. Materials for which lithium may be doped / dedoped may be lithium, alloys thereof or carbon materials. Specifically, examples of the carbon material include carbon black such as natural graphite, artificial graphite, pyrolytic carbon, coke or acetylene black, glassy carbon, activated carbon, carbon fiber, fired body of organic polymer, coffee bean fired body, cellulose fired body or There is bamboo bamboo body.

The inventors conducted extensive research and found that graphitized metocarbon microbead carbon at a firing temperature of about 2800 ° C. is a preferred material. Metocarbon microbead carbon has higher electrochemical stability than electrolyte. Therefore, it may be effective when it is combined with a gel electrolyte of a type suitable for an electrolyte containing polypropylene carbonate.

The mean particle size of the metocarbon microbead carbon is preferably between 6 μm and 25 μm. As the average particle size of metocarbon microbead carbon decreases, overvoltage in the electrode reaction can be reduced. As a result, the output characteristics of the battery can be improved. In order to increase the electrode packing density, it is advantageous to increase the average particle size. Therefore, preference is given to using methocarbon microbead carbons having an average particle size in the range of 6 μm to 25 μm.

FIG. 5 shows a state where the gel electrolyte layer 4 to be described later is formed on the negative electrode active material layer 3a of the negative electrode 3.

The gel electrolyte layer 4 contains an electrolyte salt, a matrix polymer and a swelling solvent used as a plasticizer.

The electrolyte salt may be any one of LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiAsF ₆ , LiBF ₄ , LiN (CF ₃ SO ₃ ) ₂ and C ₄ F ₉ SO ₃ Li, which may be used alone or in combination have. In particular, it is preferable to use LiPF ₆ from the viewpoint of obtaining satisfactory ion conductivity.

The matrix polymer should be at least 1 mS / cm at room temperature in the form of a single species polymer or gel electrolyte. If the ion conductivity is realized, the chemical structure of the matrix polymer is not limited. Examples of matrix polymers are polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polysiloxane compounds, polyphosphagen compounds, polypropylene oxide, polymethylmethacrylate, polymethacrylonitrile and polyether compounds. The material obtained by copolymerizing the said polymer and another polymer can also be used. In view of realizing chemical safety and ion conductivity, materials having a copolymerization ratio of vinylidene fluoride to hexafluoropropylene of less than 8% by weight are used.

The swelling solvent may be a non-aqueous solvent, for example ethylene carbonate, propylene carbonate, γ-butylollactone, acetonitrile, diethyl ether, diethyl carbonate, dimethyl carbonate, 1,2 -Dimethoxyethane, dimethylsulfoxide, 1,3-dioxolane, methylsulfonate, 2-methyltetrahydrofuran, tetrahydrofuran, sulfolane, 2,4-difluoroanisole and vinyl carbonate. The materials may be used alone or in mixtures thereof.

In particular, it is preferable to use a material such as ethylene carbonate, propylene carbonate, or γ-butylolactone having a relatively large potential window. The potential window is the potential region where the solvent can be stably present.

When 2,4-difluoroanisole or vinylene carbonate is added in an amount of 0.5 to 5% by weight relative to the total weight of the solvent, the properties of the cell can sometimes be improved.

The gel electrolyte layer 4 is preferably configured such that the mixing ratio of the matrix polymer and the swelling solvent is 1: 5 to 1:10. When the amount of the swelling solvent is less than five times the amount of the matrix polymer, the electrolyte component in the gel electrolyte is too small. Thus, the ion conductivity of the gel electrolyte layer 4 is lowered. If the amount of the swelling solvent is more than 10 times that of the matrix polymer, the gel electrolyte is embrittled. Thus, satisfactory liquid storage performance of the matrix polymer cannot be obtained.

When the mixing ratio of the matrix polymer and the swelling solvent satisfies the above range, the liquid retention performance of the matrix polymer can be maintained. The ion conductivity of the gel electrolyte layer 4 can also be maintained.

It is preferable that the thickness of the gel electrolyte layer 4 is 5 micrometers-19 micrometers. When the thickness of the gel electrolyte layer 4 is smaller than 5 mu m, the amount of gel that can smoothly proceed the electrode reaction cannot be easily obtained. When the thickness of the gel electrolyte layer 4 is larger than 19 mu m, the distance between the positive electrode 2 and the negative electrode 3 increases. As the distance between the two electrodes increases, the energy density and output characteristics of the cell significantly degrade. Therefore, the thickness of the gel electrolyte layer 4 is manufactured so that it is 5 micrometers-19 micrometers. Therefore, the decrease in the energy density and the output characteristics of the battery can be prevented during the electrode reaction.

The separator 5 disposed between the anode 2 and the cathode 3 prevents a short circuit resulting from the physical contact between the anode 2 and the cathode 3.

The thickness of the separator 5 according to the present embodiment satisfies the range of 5 μm to 15 μm. When the thickness of the separator 5 is smaller than 5 μm, the separator 5 may not be easy to handle during battery production. As a result, the production yield of the gel electrolyte battery 1 is lowered. When the thickness of the separator 5 is larger than 15 µm, the internal resistance of the gel electrolyte cell 1 increases excessively. Moreover, since the energy density loss increases, the thickness of the separator 5 is in the range of 5 µm to 15 µm. Therefore, it is possible to prevent a decrease in the production yield of the gel electrolyte cell 1, an increase in internal resistance, and an increase in energy density loss.

The porosity of the separator 5 according to the present embodiment satisfies the range of 25% to 60%. When the porosity of the separator 5 is less than 25%, the internal resistance of the gel electrolyte cell 1 excessively increases, so that a predetermined output characteristic cannot be obtained. When the porosity of the separator 5 is larger than 60%, satisfactory mechanical strength cannot be easily realized, so that the porosity of the separator 5 is in the range of 25% to 60%. Therefore, the mechanical strength of the separator 5 can be maintained without increasing the internal resistance of the gel electrolyte cell 1.

The separator 5 according to the present embodiment has a shutdown effect when the temperature of the battery is in the range of 100 ° C to 160 ° C. In order to obtain the shutdown effect, when the temperature of the battery is in the range of 100 ° C to 160 ° C, the melting point of the material of the separator 5 should be in the range of 100 ° C to 160 ° C. Since the separator 5 is disposed between the electrodes, the separator 5 must have electrochemical stability.

"Shutdown effect is obtained when the temperature of the separator 5 is in the range of 100 ° C to 160 ° C", which means that the internal impedance of the cell is increased by at least two orders of magnitude when the battery temperature is in the range of 100 ° C to 160 ° C. .

Polyolefin polymers are typical as materials satisfying the above conditions, and examples thereof include polyethylene or polypropylene. In particular, the separator 5 is preferably made of polyethylene. Another polyolefin polymer is copolymerized or blended with polyethylene or polypropylene using a type of resin that has chemical safety for gel electrolytes.

As described above, the separator 5 has a shutdown effect when the thickness satisfies the range of 5 μm to 15 μm, the porosity that satisfies the range of 25% to 60% and the temperature satisfies the range of 100 ° C. to 160 ° C. Therefore, the energy density of the gel electrolyte cell 1 can be increased, and the safety can be improved.

In addition, the inventors of the present invention have intensively studied the relationship between the physical properties of the separator 5 and the characteristics of the battery. As a result, the following facts were found. The separator 5 preferably has a thickness in the range of 5 μm to 15 μm, a porosity in the range of 25% to 60%, a breaking strength of less than 1650 kg / cm 2, and an elongation at break of 135% or more. When the breaking strength and the breaking elongation of the separator 5 do not satisfy the above ranges, the separator 5 may not be easy to handle in the manufacture of the gel electrolyte battery 1. Therefore, the production yield of the gel electrolyte cell 1 is limited. Moreover, satisfactory properties of the battery cannot be obtained. Therefore, the use of the separator 5 having a breaking strength of less than 1650 kg / cm 2 and an elongation at break of 135% or more can prevent a decrease in the production yield of the gel electrolyte battery 1. Thus, satisfactory characteristics of the gel electrolyte cell 1 can be obtained.

In order to evaluate the breaking strength and the elongation at break of the separator 5, a tensile test of the separator 5 was performed as follows.

A test piece of the separator 5 in the form of a substantially 30 mm x 70 mm rectangle is cut out. A 10 mm wide cellophane tape was then attached to each of the longitudinal ends of the test pieces.

Subsequently, the obtained test piece was sufficiently fixed to the sample clamping portion of the tensile test apparatus. Tensile testing devices are, for example, model NO. 1310f (manufactured by Aiko). The part of the test piece that is held by the sample clamping part is the part reinforced with cellophane tape. That is, a portion of the 50 mm long test pieces were tensile tested except for the reinforced ends, each 10 mm long.

In this state, after confirming that the test piece was placed perpendicular to the test apparatus table, the tensile test was started. Tensile strength is 40 mm per minute. Data on load values and elongation values were recorded by a personal computer via an A / D conversion board. According to the data obtained, the breaking strength and the elongation at break were calculated. The load that caused the test piece to break was used as the breaking strength. The elongation at break (%) was determined using Equation 1 by measuring the length (mm) of the test piece immediately before the test piece was broken.

Elongation at break = 100 X (length of test fragment immediately before break / 50). (Equation 1)

As a result of performing the above measuring method, the breaking strength of the separator 5 according to the present embodiment was less than 1650 kg / cm 3, and the elongation at break was 135% or more. When using the separator 5 which satisfy | fills the said mechanical characteristic, the manufacturing yield of the gel electrolyte battery 1 can be prevented from falling. In addition, satisfactory battery characteristics can be obtained.

As described above, the separator 5 used has a thickness of 5 µm to 15 µm, a porosity of 25% to 60%, a breaking strength of less than 1650 kg / cm 3, and an elongation at break of 135% or more. Thus, high energy density and safety of the gel electrolyte cell 1 can be realized.

One of the purposes of the separator 5 is to prevent internal short circuits resulting from physical contact between the positive electrode 2 and the negative electrode 3. The size of the separator 5 depends on the size of the positive electrode 2 and the negative electrode 3 and the shape of the battery element. That is, the opposite electrodes must be completely insulated from each other by the separator 5. The electrode terminals and the electrodes must also be insulated from each other by the separator 5. In order to realize the above state, the separator 5 must be larger than the total size of each of the positive electrode 2 and the negative electrode 3.

It has been found from the experiment that the separator 5 according to the present embodiment forms a fine structure of a so-called fibril structure as shown in FIG. 6. 6 is a microstructure photograph of the wound electrode 6 taken 50,000 times in magnification with an electron microscope.

As a method for obtaining the fibrillated separator 5, a number of methods were used. An example of such a method is described below.

First, a molten liquid of a low volatility solvent (a good solvent for the polyolefin composition) was fed to an extruder containing the molten polyolefin composition to be kneaded. Thus, high concentration solutions of polyolefin compositions with constant concentration were prepared.

Examples of polyolefins are polyethylene and polypropylene. Preference is given to using polyethylene. Examples of low volatile solvents are low volatile aliphatic hydrocarbons or cyclic hydrocarbons such as nonane, decane, decalin, p-xylene, undecane or liquid paraffin.

The mixing ratio of the polyolefin composition and the low volatile solvent is in the range of 10 parts by weight to 80 parts by weight, preferably 15 parts by weight to 70 parts by weight based on 100 parts by weight of the total weight of the two materials. If the amount of polyolefin composition is less than 10 parts by weight, swelling or neck-in occurs excessively at the outlet of the die. In this case, the required sheet cannot be easily formed. When the amount of the polyolefin composition is 80 parts by weight or more, a homogeneous solution cannot be easily produced. Therefore, the proportion of polyolefin is in the range of 10 to 80 parts by weight. Thus, the preparation of the homogeneous solvent and the formation of the sheet can be easily performed.

The heated solution of the polyolefin composition is extruded through a die to obtain a sheet of the polyolefin composition solution and then cooled to obtain a gel sheet. The cooling process is performed until the temperature is lower than the gelling temperature. The following cooling methods can be used. There is a method of directly contacting cold air, cold water or other refrigerant, or a roll cooling contact with a coolant.

The polyolefin composition solution extruded from the die may be drawn at a pulling ratio of 1 to 10, preferably 1 to 5. When the take-over ratio is 10 or more, larger neck-in occurs and breakage easily occurs. When the take-off ratio is in the range of 1 to 10, neck-in and breaking of the gel sheet can be prevented.

Subsequently, the obtained gel-like sheet is heated so that it may be stretched by a predetermined magnification to obtain a stretched film. The gel sheet is stretched by the usual tenter method, roll method, milling method, or a combination of these methods. It is preferable to use the biaxial stretching method. Biaxial stretching may be longitudinal or simultaneous stretching or sequential stretching. In particular, it is preferable to use simultaneous biaxial stretching.

It is preferable to extend a gel sheet at the temperature of melting | fusing point +10 degrees C or less of a polyolefin composition. More preferably, the stretching temperature ranges from the crystal dispersion temperature of the polyolefin composition to its melting point temperature. When the stretching temperature is at the melting point of the polyolefin composition + 10 ° C. or more, the resin melts undesirably. In this case, the molecule cannot be effectively stretched. If the stretching temperature is lower than the crystal dispersion temperature, the resin cannot be softened sufficiently. In such a case, breakage easily occurs during the stretching process, and thus high magnification stretching cannot be performed. When the extending | stretching temperature of a gel-like sheet satisfy | fills the said range, extending | stretching of uniform high magnification can be performed. In addition, the stretching of the molecular chain can be effectively performed.

The resulting stretched film is washed with volatile solvent to remove residual low volatile solvent. The volatile solvent used for the cleaning process may be a basic hydrocarbon such as pentane, hexane or heptane, hydrogen fluoride such as ethane trifluoride, ether such as diethyl ether or dioxane. The materials may be used alone or in combination. The solvent for washing of the stretched film may be appropriately selected to be suitable for the low volatility solvent used to dissolve the polypropylene composition.

The stretched film can be washed by immersing it in a solvent to extract the remaining low-volatile solvent, pouring the solvent into the stretched film, or a combination thereof. The stretched film is cleaned until the amount of the low volatility solvent remaining in it is less than 1 part by weight.

Finally, the solvent used to clean the stretched film is dried to remove it. The solvent is dried by heating or air spray. After completing the above steps, the separator 5 according to the present embodiment can be obtained. The separator 5 thus obtained has a fibril structure as shown in FIG.

According to the present embodiment, the gel electrolyte cell 1 including the separator 5 is produced as follows.

The positive electrode 2 is manufactured as follows. The positive electrode mixture containing the positive electrode active material and the binder is uniformly applied to the surface of the metal foil to be formed of the positive electrode current collector 2b, for example, aluminum foil, and then the positive electrode mixture is dried. Thus, the positive electrode active material layer 2a is formed to produce a positive electrode sheet. The binder of the positive electrode mixture may be a known binder. Known additives may be added to the positive electrode mixture.

The gel electrolyte layer 4 is then formed on the positive electrode active material layer 2a of the positive electrode sheet. In order to form the gel electrolyte layer 4, as a first step, an electrolyte salt is dissolved in a non-aqueous solvent to prepare a non-aqueous electrolyte solution. The matrix polymer is then added to the non-aqueous electrolyte solution, and then the solution is sufficiently stirred to dissolve the matrix polymer. Thus, a sol electrolyte solution is prepared.

A predetermined amount of electrolyte solution is then applied to the surface of the positive electrode active material layer 2a. The positive electrode active material layer 2a is then cooled to room temperature to gel the matrix polymer. Thus, the gel electrolyte layer 4 is formed on the positive electrode active material layer 2a.

Next, the positive electrode sheet on which the gel electrolyte layer 4 is formed is cut to obtain a strip-shaped member. The aluminum lead is welded to a portion of the positive electrode current collector 2b in which the positive electrode active material layer 2a is not formed to form the positive electrode terminal 8. Subsequently, a band-shaped anode 2 in which the gel electrolyte layer 4 is formed can be obtained.

The negative electrode 3 is manufactured as follows. The negative electrode mixture containing the negative electrode active material and the binder is uniformly applied to the surface of the metal foil to be formed of the negative electrode current collector 3b, for example, copper foil. Next, the metal foil is dried. Thus, a negative electrode sheet on which the negative electrode active material layer 3a is formed is produced. The binder of the negative electrode mixture may be a known binder. Known additives may be added to the negative electrode mixture.

The gel electrolyte layer 4 is then formed on the negative electrode current collector 3b. In order to form the gel electrolyte layer 4, an electrolyte solution prepared by carrying out similar steps to the above process is applied to the surface of the negative electrode active material layer in a predetermined amount. The layer of negative electrode active material is then dried at room temperature to gel the matrix polymer. As a result, the gel electrolyte layer 4 is formed on the negative electrode current collector 3b.

Next, the negative electrode sheet on which the gel electrolyte layer 4 is formed is cut to obtain a strip-shaped member. For example, a lead made of nickel is welded to a portion of the negative electrode current collector 3b in which the negative electrode active material layer 3a is not formed. Thus, the negative electrode terminal 9 is formed. Thus, a band-shaped negative electrode 3 in which the gel electrolyte layer 4 is formed is formed.

Subsequently, the surfaces of the strip-shaped anode 2 and the cathode 3, each of which was prepared as described above, on which the gel electrolyte layer 4 was formed, were disposed to face each other. The separator 5 is inserted and attached between the positive electrode 2 and the negative electrode 3, and compressed to obtain an electrode laminate. Next, the electrode laminate is wound in the longitudinal direction to obtain a wound electrode 6.

Finally, the wound electrode 6 is inserted between the outer film 7. Next, the resin film 10 is arrange | positioned in each part which the positive electrode terminal 8, the negative electrode terminal 9, and the exterior film 7 overlap. Next, the periphery of the exterior film 7 is sealed. The positive terminal 8 and the negative terminal 9 are then inserted into the sealing opening of the exterior film 7. In addition, the wound electrode 6 is hermetically sealed between the outer film 7. With the wound electrode 6 packed in the outer film 7, the wound electrode 6 is heat treated. Thus, the gel electrolyte cell 1 can be produced.

When the wound electrode 6 is packed into the outer film 7, the resin film 10 is contacted between the outer film 7 and the positive terminal 8 and between the outer film 7 and the negative terminal 9. Place in each. Therefore, generation | occurrence | production of the short circuit resulting from plating plates, such as the exterior film 7, can be prevented. In addition, the adhesive force between the exterior film 7 and the positive terminal 8 and between the exterior film 7 and the negative terminal 9 can be improved.

The resin film 10 may be made of a material having adhesion to the positive terminal 8 and the negative terminal 9. If the material has the adhesion as described above, the material is non-limiting, and preferably any of polyethylene, polypropylene, modified polyethylene, modified polypropylene, copolymers thereof and polyolefin resin can be used. It is preferable that the thickness of the resin film 10 realized before heat welding is 20 micrometers-300 micrometers. When the thickness of the resin film 10 is less than 20 micrometers, handleability will deteriorate. When the thickness is more than 300 µm, water easily permeates the resin film 10, and as a result, airtightness inside the battery is hardly preserved.

In the above embodiment, the strip positive electrode 2 and the strip negative electrode 3 are laminated. Subsequently, the laminated body is wound in the longitudinal direction to produce a wound electrode 6. The present invention is not limited to the above structure. The present invention can be applied to a structure in which the rectangular positive electrodes 2 and the rectangular negative electrodes 3 are laminated to form an electrode laminate, or a structure in which the electrode laminates are alternately folded.

In the above embodiment, the electrolyte present between the anode 2 and the cathode 3 is a gel electrolyte containing a swelling solvent. The present invention is not limited to the above structure. The present invention can be applied to a structure in which a solid electrolyte containing no swelling solvent is used.

Solid electrolytes must have an ionic conductivity of at least 1 mS / cm at room temperature. If the solid electrolyte has the above properties, the chemical structure is not limited. Examples of solid electrolytes of this type include polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polysiloxane compounds, polyphosphagen compounds, polypropylene oxide, polymethylmethacrylate, polymethacrylonitrile or polyether compounds, and the like. Organic solid electrolytes obtained by dissolving inorganic salts, ion conductive ceramic materials, ion conductive glass, and the like.

The form of the gel electrolyte cell 1 according to the present embodiment is not limited. For example, a cylindrical, rectangular, coin shape or the like can be used. The present invention can be applied to both primary and secondary batteries.

Second Embodiment

Structure examples of the gel electrolyte cell 20 according to the present embodiment are shown in Figs. The gel electrolyte cell 20 includes a stripe positive electrode 21, a stripe cathode layer 23 formed on each of the stripe negative electrode 22, the positive electrode 21, and the negative electrode 22 disposed to face the positive electrode 21, And a separator 24 with a gel electrolyte layer 23 disposed between each of the anode 21 and the cathode 22 formed thereon.

The gel electrolyte cell 20 includes an anode 21 on which a gel electrolyte layer 23 is formed and a cathode 22 on which a gel electrolyte layer 23 is formed. The positive electrode 21 and the negative electrode 22 are laminated through the separator 24 and wound in the longitudinal direction to form a wound electrode 25 structure as shown in FIG. The wound electrode 25 is covered with an outer film 26 and made of an insulating material so that the wound electrode 25 is sealed with an outer film 26. The positive terminal 27 is connected to the positive electrode 21, while the negative terminal 28 is connected to the negative electrode 22. The positive terminal 27 and the negative terminal 28 are inserted between the sealing openings which are the circumference of the exterior film 26. The resin film 29 is provided at the portion where the positive terminal 27 and the negative terminal 28 contact the exterior film 26.

As shown in Fig. 10, the positive electrode 21 contains a positive electrode active material and includes a positive electrode active material layer 21a formed on the positive electrode current collector 21b. The positive electrode current collector 21b may be made of a metal foil such as aluminum foil.

The positive electrode active material may be a material from which positive ions can be implanted and separated. An example of such ions is lithium ions. Specifically, examples of the positive electrode active material are LiCoO ₂ , LiNiO ₂ and LiMn ₂ O ₄ . Two or more kinds or one kind of transition metal elements may be used. Specifically, LiNi _0.5 Co _0.5 O ₂ or the like may be used.

The positive electrode active material layer 21a is manufactured as follows. The positive electrode active material, the carbon material as the conductive material, and the polyvinylidene fluoride as the binder are mixed. Subsequently, N-methylpyrrolidone is added as a solvent to prepare a slurry. The obtained slurry is uniformly added to the aluminum foil surface by a doctor blade method to form a positive electrode current collector. The aluminum foil is then dried at high temperature to remove N-methylpyrrolidone.

The mixing ratio of the positive electrode active material, the conductive material, the binder and the N-methylpyrrolidone is not limited. Mixing ratios are a problem in forming a slurry in which the mixture is uniformly dispersed.

FIG. 10 shows a state where the gel electrolyte layer 23 to be described later is formed on the positive electrode active material layer 21a of the positive electrode 21.

As shown in FIG. 11, the negative electrode 22 contains a negative electrode active material and includes a negative electrode active material layer 22a formed on the negative electrode current collector 22b. The negative electrode current collector 22b is made of metal foil such as copper foil, for example.

The negative electrode active material is a material capable of injecting and separating Li, for example, graphite, non-graphitized carbon or graphitized carbon.

The negative electrode active material layer 22a is prepared as follows. The negative electrode active material and the binder polyvinylidene fluoride are mixed with each other. Subsequently, N-methylpyrrolidone is added as a solvent to prepare a slurry. The obtained slurry is uniformly applied to the copper foil surface by a doctor blade method to form a negative electrode current collector. The copper foil is then dried at high temperature to remove N-methylpyrrolidone. Subsequently, the negative electrode active material layer 22a is formed.

Mixing is performed at a constant mixing ratio of the negative electrode active material, the binder, and N-methylpyrrolidone to prepare a slurry in which the mixture is uniformly dispersed. Here, the mixing ratio is not limited. "Liquid injection and separation are possible" means that the implantation and removal of Li into the crystal structure is not restricted. If charge and discharge are allowed in the cell, the possibility of injection and separation is determined. Examples of the negative electrode are a Li negative electrode and a Li-Al alloy negative electrode.

FIG. 11 shows a state where a gel electrolyte layer 23 to be described later is formed on the negative electrode active material layer 22a of the negative electrode 22.

The gel electrolyte layer 23 contains an electrolyte salt, a matrix polymer and a swelling agent used as a plasticizer.

The matrix polymer must be compatible with the solvent. Examples are polyacrylonitrile, polyethylene oxide polymers, polyvinylidene fluorides, copolymers of polyvinylidene fluoride and hexafluoropropylene, styrene-butadiene rubber and polymethylmethacrylate. Two or more kinds of matrix polymers may be used as well as a single kind of matrix. Although not included in the examples above, those that are compatible with the solvent and form the gel can be used.

The solvent is a solvent that can be dispersed in the matrix polymer. Examples of aprotic solvents are ethylene carbonate, propylene carbonate, butylene carbonate, γ-butylollactone, diethyl carbonate, dimethyl carbonate, ethylmethyl carbonate and dimethoxyethane . One kind or two or more kinds of the above materials may be used.

The electrolyte salt must be dissolved in the solvent. Examples of cations are alkali metals and alkaline earth metals. Examples of the anion is ^{Cl -, Br -, I -} , SCN -, ClO 4 -, BF 4 -, PF 6 - CF 3 SO 3 - and _{(CF 3 SO 2) 2 N} - is. The concentration of the electrolyte salt should be such that the electrolyte salt can be dissolved in the solvent.

It is preferable that the thickness of the gel electrolyte layer 23 is 5 micrometers-15 micrometers. When the thickness of the gel electrolyte layer 23 is thinner than 5 mu m, a short circuit resulting from contact between the positive electrode and the negative electrode cannot be sufficiently prevented. When the thickness of the gel electrolyte layer 23 is thicker than 15 µm, the resistance to high load is degraded and the volume energy density is lowered.

The separator 24 is disposed between the positive electrode 21 and the negative electrode 22 to prevent a short circuit resulting from the physical contact between the positive electrode 21 and the negative electrode 22. The separator 24 according to this embodiment consists of a composite of polyethylene and polypropylene obtained by adding polypropylene to polyethylene. When the separator 24 is composed of a composite of polyethylene and polypropylene, only the meltdown temperature can be raised, while the shutdown temperature of the separator 24 similar to the polyethylene separator can be maintained.

Specifically, the meltdown temperature of the separator 24 is preferably 10 ° C to 30 ° C higher than the meltdown temperature of the polypropylene separator. The meltdown temperature is the temperature at which shutdown separator 24 melts and breaks.
If the meltdown temperature of the separator 24 is higher than 10 ° C higher than the meltdown temperature of the polyethylene separator, the effect of the present invention of raising the meltdown temperature cannot be satisfactorily obtained. The reason why the meltdown temperature of the separator 24 is 30 degrees C or less higher than the meltdown temperature of the polyethylene separator will be explained below. The difference in meltdown temperature between the polypropylene separator and the polyethylene separator is about 30 ° C.

It is preferable that the thickness of the separator 24 which concerns on this embodiment is 5 micrometers-15 micrometers. When the thickness of the separator 24 is thinner than 5 μm, the separator 24 may not be easy to handle during battery production. As a result, the manufacturing yield of a battery falls. When the thickness of the separator 24 is thicker than 15 m, the internal resistance of the battery increases. Moreover, energy density losses increase to an undesirable extent. Thus, the thickness of the separator 24 is in the range of 5 μm to 15 μm. Therefore, it is possible to prevent a decrease in the production yield of the battery, an increase in internal resistance, and an increase in energy density loss.

The porosity of the separator 24 is preferably in the range of 25% to 60%. When the porosity of the separator 24 is less than 25%, the internal resistance of the battery is excessively increased so that a certain output characteristic cannot be obtained. When the porosity of the separator 24 is larger than 60%, satisfactory mechanical strength cannot be easily obtained. Therefore, the porosity of the separator 24 is in the range of 25% to 60%. Thus, the mechanical strength of the separator 24 can be maintained without increasing the internal resistance of the battery.

As above, the separator 24 which concerns on this embodiment is manufactured as follows, for example. Note that the manufacturing method of the separator 24 is not limited to the following specific values. The mixing ratio of polyethylene and polypropylene constituting the separator 24 is also not limited to the following values.

First, 20% by weight ultra high molecular weight polyethylene (UHMWPE) having a weight average molecular weight Mw of 2.5 X 10 ⁶ , 30% by weight of high density polyethylene (HDPE) having a weight average molecular weight Mw of 3.5 X 10 ⁵ and a weight average molecular weight Mw of 5.1 X 10 ⁵ A polyolefin composition is prepared by adding 0.375 parts by weight of an oxidation inhibitor to 100 parts by weight of a polyolefin mixture including 50% by weight of phosphorus polypropylene.

Next, 30 parts by weight of the polyolefin composition is introduced into a twin screw extruder (58 mm in diameter, L / D = 42, strong kneading type). In addition, 70 parts by weight of liquid paraffin was supplied through a side feeder to melt kneading at 200 rpm to prepare a polyolefin solution in an extruder.

The polyolefin solution is then extruded at 190 ° C. so as to be wound around a chill roll from a T-die installed at the tip of the extruder. Thus, the gel sheet is molded. The gel sheet is then biaxially stretched at 115 ° C. to obtain a 5 × 5 stretched film. The resulting stretched membrane is washed with methylene chloride to extract and remove liquid paraffin. The stretched film is then dried and heat treated. Thus, a microporous separator 24 composed of a composite material of polyethylene and polypropylene is obtained.

The separator 24 according to the present embodiment composed of a composite material of polyethylene and polypropylene may be constituted by attaching a separator 24a composed of polyethylene and a separator 24b composed of polypropylene to each other as shown in FIG. 12. When the separator 24a composed of polyethylene and the separator 24b composed of polypropylene are attached to each other, the meltdown temperature of the separator 24 can be raised to the meltdown temperature of the polypropylene, while shutting down the separator 24. The temperature can be maintained at the shutdown temperature of the polyethylene.

The reason for attaching each of the separator 24a composed of polyethylene and the separator 24b composed of polypropylene to each other will be described below. When three or more kinds of separators are superimposed, the thickness of the separator becomes considerably thicker, and an increase in battery internal resistance cannot be prevented. Therefore, there is a problem that the energy density loss becomes undesirably large. Thus, the separator 24a made of polyethylene and the separator 24b made of polypropylene are attached to each other so that the thickness of the separator is reduced as much as possible. Thus, the maximum effect can be obtained.

When the separator 24 is made of the above attachment structure, the thickness of each of the separator 24a composed of polyethylene and the separator 24b composed of polypropylene is preferably in the range of 2.5 µm to 7.5 µm. In addition, it is preferable that the total thickness of two types of separators is 5 micrometers-15 micrometers. When the thickness of the separator 24 is thinner than 5 μm, the separator 24 may not be easy to handle during battery production. Therefore, the manufacturing yield of a battery falls. When the thickness of the separator 24 is thicker than 15 m, the internal resistance of the battery is excessively increased. Moreover, the problem of energy density loss becomes large. Thus, the thickness of the separator 24 is in the range of 5 μm to 15 μm. Thereby, it is possible to prevent the decrease in the production yield of the battery, the increase in the internal resistance and the increase in energy density loss.

The width of the separator 24 according to this embodiment of the above structure should be larger than the width of each of the positive electrode 21 and the negative electrode 22, as shown in FIG. 13. When the positive electrode 21, the negative electrode 22, and the separator 24 are superimposed and wound on each other, deviation of the positive electrode 21, the negative electrode 22, and the separator 24 often occurs. As shown in FIG. 13, when the positive electrode 21, the negative electrode 22, and the separator 24 overlap, assuming that the width deviations are L ₁ and L ₂ , L ₁ is smaller than 0 or L ₂ is If less than zero, the positive electrode 21 and the negative electrode 22 are in contact with each other. That is, when the end of the separator 24 is inside the end of the positive electrode 21 or the negative electrode 22, contact occurs. As a result, internal short circuit occurs and the manufacturing yield of a battery falls.

Therefore, when deviation occurs during the overlapping and winding process of the positive electrode 21, the negative electrode 22, and the separator 24, contact between the positive electrode 21 and the negative electrode 22 should be prevented. Therefore, the width of the separator 24 should be somewhat larger than the width of each of the anode 21 and the cathode 22. When the width of the separator 24 is too large, the energy density of the battery decreases. Thus, as shown in Figure 13 is the width of the separator (24), L ₁ is greater than 0.5 mm, L ₂ is greater than 0.5 mm, L ₁ + L ₂ should be determined by small way than 4 mm. In the case where the width of the separator 24 is as described above, the occurrence of the internal short circuit resulting from the positive electrode 21 and the negative electrode 22 causes deviation between the positive electrode 21, the negative electrode 22 and the separator 24. You can prevent it. As a result, the fall of manufacture yield can be prevented.

The gel electrolyte cell 20 including the separator 24 according to the present embodiment is produced as follows.

First, the positive electrode 21 is manufactured as follows. The positive electrode mixture containing the positive electrode active material and the binder is uniformly applied to the surface of the metal foil to be formed of the positive electrode current collector 21b, for example, aluminum foil. The metal foil is then dried to form the positive electrode active material layer 21a. Thus, the positive electrode sheet 21 is manufactured. The binder in the positive electrode mixture may be a known binder. Known additives and the like can be added to the positive electrode mixture.

A gel electrolyte layer 23 is then formed on the positive electrode active material layer 21a of the positive electrode sheet. To form the gel electrolyte layer 23, the electrolyte salt is dissolved in a nonaqueous solvent to prepare a nonaqueous electrolyte solution. The matrix polymer is then added to the non-aqueous electrolyte solution, and then the solution is sufficiently stirred to dissolve the matrix polymer. Thus, a sol electrolyte solution is prepared.

Subsequently, a predetermined amount of electrolyte solution is applied to the surface of the positive electrode active material layer 21a. The temperature of the cathode active material layer 21a is then lowered to room temperature to gel the matrix polymer. Thus, the gel electrolyte layer 23 is formed over the positive electrode active material layer 21a.

Next, the positive electrode sheet on which the gel electrolyte layer 23 is formed is cut to obtain a strip-shaped member. For example, a conductive wire made of aluminum is welded to a portion of the positive electrode current collector 21 b in which the positive electrode active material layer 21 a is not formed to form the positive electrode terminal 27. Thus, the strip-shaped anode 21 in which the gel electrolyte layer 23 is formed can be obtained.

The cathode 22 is manufactured as follows. The negative electrode mixture containing the negative electrode active material and the binder is uniformly applied to the surface of the metal foil to be formed of the negative electrode current collector 22b, for example, copper foil. The metal foil is then dried to form the negative electrode active material layer 22a. Thus, a negative electrode sheet is produced. The binder in the negative electrode mixture may be a known binder. Known additives and the like can be added to the negative electrode mixture.

Next, a gel electrolyte layer 23 is formed on the negative electrode current collector 22b of the negative electrode sheet. In order to form the gel electrolyte layer 23, an electrolyte solution prepared similarly to the above process is applied to the negative electrode active material layer in a predetermined amount. The temperature of the negative electrode active material layer is then cooled to room temperature to gel the matrix polymer. As a result, the gel electrolyte layer 23 is formed on the negative electrode current collector 22b.

Next, the negative electrode sheet on which the gel electrolyte layer 23 is formed is cut to obtain a strip-shaped member. Subsequently, a conductive wire made of, for example, nickel is welded to a portion of the negative electrode current collector 22b in which the negative electrode active material layer 22a is not formed to form the negative electrode terminal 28. Thus, a band-shaped negative electrode 22 in which the gel electrolyte layer 23 is formed is formed.

The gel electrolyte layers 23 formed on the surfaces of the strip-shaped anode 21 and the cathode 22 prepared as described above are disposed to face each other. Next, the separator 24 is placed between the positive electrode 21 and the negative electrode 22 to be crimped. Thus, an electrode laminate is obtained. Next, the electrode laminate is wound in the longitudinal direction to obtain a wound electrode 25.

Finally, the wound electrode 25 is inserted between the outer film 26 made of an insulating material. Next, the resin film 29 is disposed in each of the portions where the positive electrode terminal 27 and the negative electrode terminal 28 overlap with the exterior film 26. Then, the circumference of the exterior film 26 is sealed so that the positive terminal 27 and the negative terminal 28 are inserted into the seal of the exterior film 26. In addition, the wound electrode 25 is hermetically sealed between the outer film 26. Thus, the gel electrolyte cell 20 is manufactured.

As shown in FIG. 14, the exterior film 26 includes a first polyethylene terephthalate layer 26a, an aluminum layer 26b, a second polyethylene terephthalate layer 26c, and a linear and low density polyethylene layer 26d. It is constructed by successive stacking. The linear and low density polyethylene layer 26d is used as the heat welding layer. In the case of sealing the wound electrode 25, the linear and low density polyethylene layer 26d is disposed therein. The thermal weld layer may be composed of materials such as polyethylene terephthalate, nylon, cast polypropylene or high density polyethylene, as well as linear and low density polyethylene.

The structure of the exterior film 26 is not limited to the above structure. At least one kind of aluminum layer and a heat sealable polymer film is necessary to exist on at least one surface.

When packing the wound electrode 25 into the outer film 26, the resin film 29 is disposed in each of the contact portions between the outer film 26, the positive terminal 27 and the negative terminal 28. Therefore, generation | occurrence | production of the short circuit resulting from plating plates, such as the exterior film 26, can be prevented. Also, the adhesive force between the exterior film 26 and the positive terminal 27 or between the exterior film 26 and the negative terminal 28 can be improved.

The material of the resin film 29 should have adhesion to the positive terminal 27 and the negative terminal 28. The material is not limited if the above requirements are met. Preferably, any of polyethylene, polypropylene, modified polyethylene, modified polypropylene, copolymers thereof and polyolefin resin can be used. It is preferable that the thickness of the resin film 29 before heat welding is 20 micrometers-300 micrometers. When the thickness of the resin film 29 is thinner than 20 micrometers, handleability will deteriorate. If the thickness is thicker than 300 mu m, water easily penetrates and it is difficult to preserve the airtightness inside the battery.

In the above embodiment, the strip positive electrode 21 and the strip negative electrode 22 are laminated. Subsequently, the laminated body is wound in the longitudinal direction to produce a wound electrode 25. The present invention is not limited to the above structure. Rectangular anode 21 and rectangular cathode 22 can be laminated to form a wired electrode. Another structure in which the electrode stacks are alternately folded may be used.

 In the above embodiment, the electrolyte inserted between the positive electrode 21 and the negative electrode 22 is a gel electrolyte containing a matrix polymer, an electrolyte salt and a solvent. The present invention is not limited to the above structure. The present invention can be applied to a structure in which a solid electrolyte containing no solvent is used and a structure in which an electrolyte solution containing no matrix polymer is used.

The form of the gel electrolyte cell 20 according to the present embodiment is not limited. For example, a cylindrical, rectangular, coin shaped or the like may be used. In addition, the size may be of various sizes, including thin structures and large size structures. The present invention can be applied to both primary and secondary batteries.

<Example>

In order to confirm the effect of the present invention, a battery having a structure as described above was produced and its characteristics were evaluated.

First embodiment

In Examples 1 to 7 and Comparative Example 1, a battery was prepared using the separator according to the first embodiment of the present invention and its properties were evaluated.

Preparation of Sample Cells

Example 1

First, a positive electrode was prepared.

First, commercial lithium carbonate and cobalt carbonate were mixed with each other so that the composition ratio of the amount of lithium atoms to cobalt atoms was 1: 1. The mixture was then baked at 900 ° C. for 5 hours in air. Subsequently, lithium cobalt acid used as the positive electrode active material was obtained. The average particle size of lithium cobaltate was 10 μm.

Subsequently, a positive electrode mixture was prepared by mixing 91 parts by weight of the obtained positive electrode active material, 6 parts by weight of graphite used as the conductive material, and 3 parts by weight of polyvinylidene fluoride used as the binder. The positive electrode mixture was then dispersed in N-methyl-2-pyrrolidone to form a paste.

Next, the obtained positive electrode mixture paste was uniformly applied on both sides of the strip-shaped aluminum foil serving as a positive electrode current collector in a thickness of 20 μm. Then, the aluminum foil was dried. After the drying process, it was pressed with a roller press and molded into aluminum foil. Thus, a positive electrode active material layer having a thickness of 40 mu m was formed. Subsequently, a conductive wire made of aluminum was welded to a portion of the positive electrode current collector in which no positive electrode active material layer was formed. Thus, a positive terminal was formed. As a result, a positive electrode was produced. The density of the positive electrode active material layer was 3.6 g / cm ³ .

Subsequently, a negative electrode was prepared as follows.

First, metocarbon microbeads having an average particle size of 25 μm were baked at 2800 ° C. to obtain graphite to be used as a negative electrode active material.

Subsequently, 90 parts by weight of the obtained negative electrode active material and 10 parts by weight of polyvinylidene fluoride were mixed to prepare a negative electrode mixture. The negative electrode mixture was then dispersed in N-methyl-2-pyrrolidone used as solvent to form a paste.

Subsequently, the obtained negative electrode mixture paste was uniformly applied to both sides of the strip-shaped aluminum foil to serve as a negative electrode current collector with a thickness of 15 μm. Subsequently, a drying process was performed. After the strip copper foil was dried, the roller press was operated to perform compression molding. Thus, a negative electrode active material layer having a thickness of 55 mu m was formed. Subsequently, a nickel terminal was welded to a portion of the negative electrode current collector where the negative electrode active material layer was not formed to form a negative electrode terminal. The density of the negative electrode active material layer was then 1.6 g / cm ³ .

Then, a gel electrolyte layer was formed on each of the negative electrode and the positive electrode.

First, 80 g of dimethyl carbonate, 40 g of ethylene carbonate, 40 g of propylene carbonate, 9.2 g of LiPF ₆ , 0.8 g of vinylene carbonate and 0.8 g of 2,4-difluoroanisole were mixed together To prepare a solution. Then 10 g of a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP) (copolymer weight ratio of VdF: HFP = 97: 3) was added to the solution. Then, it was uniformly dispersed using a homogenizer. Subsequently, heating and stirring were carried out at 75 ° C. until it was colorless and transparent. Thus, an electrolyte solution was produced.

Next, the obtained electrolyte solution was uniformly applied to both surfaces of the positive electrode and the negative electrode by the doctor blade method. Subsequently, the positive electrode and the negative electrode to which the electrolyte solution was applied were dried for 1 minute in a drying apparatus in which the inside was maintained at 40 ° C. Thus, the electrolyte solution was gelated to form a gel electrolyte layer having a thickness of about 8 μm on both sides of the positive electrode and the negative electrode.

The battery was then assembled as follows.

First, a band-shaped positive electrode and a negative electrode prepared as described above, each having a gel electrolyte layer formed on both surfaces thereof, were laminated through a separator to obtain a laminate. Next, the laminate was wound in the longitudinal direction to obtain a wound electrode. The separator was a porous polyethylene membrane having a porosity of 36% and a thickness of 8 mu m.

The wire-shaped electrode was inserted between the waterproof sheet film formed by laminating a nylon sheet having a thickness of 25 μm, an aluminum sheet having a thickness of 40 μm, and a polypropylene sheet having a thickness of 30 μm. Then, the circumference of the exterior film was heat-sealed under reduced pressure and sealed. Therefore, the wound electrode was hermetically sealed in the outer film. At this time, the positive terminal and the negative terminal were inserted into the sealing portion of the outer film. In addition, the polyolefin film was dispersed in each part where the exterior film, the positive electrode terminal, and the negative electrode contact each other.

Finally, the electrode element was heat-treated in the state in which the electrode terminal was enclosed in the exterior film, and the gel electrolyte battery was produced.

Example 2                     

In this example, the same procedure as in Example 1 was carried out except that a separator made of a porous polyethylene membrane having a porosity of 37% and a thickness of 9 μm was used. Thus, a gel electrolyte cell was produced.

Example 3

In the present Example was carried out in the same manner as in Example 1 except for using a separator made of a porous polyethylene membrane having a porosity of 35% and a thickness of 10 ㎛. Thus, a gel electrolyte cell was produced.

Example 4

In the present Example was carried out in the same manner as in Example 1 except for using a separator made of a porous polyethylene membrane having a porosity of 30% and a thickness of 12 ㎛. Thus, a gel electrolyte cell was produced.

Example 5

In the present Example was carried out in the same manner as in Example 1 except for using a separator made of a porous polyethylene membrane having a porosity of 39% and a thickness of 15 ㎛. Thus, a gel electrolyte cell was produced.

Example 6

In the present Example was carried out in the same manner as in Example 1 except for using a separator made of a porous polyethylene membrane having a porosity of 36% and a thickness of 8 ㎛. Thus, a gel electrolyte cell was produced.

Example 7                     

In the present Example was carried out in the same manner as in Example 1 except for using a separator made of a porous polyethylene membrane having a porosity of 36% and a thickness of 16 ㎛. Thus, a gel electrolyte cell was produced.

Comparative Example 1

In this comparative example was carried out in the same manner as in Example 1 except that no separator was included. Thus, a gel electrolyte cell was produced.

Characterization of Sample Cells

The material, porosity, thickness, breaking strength and elongation at break of the separator according to Examples 1 to 7 of the present invention are shown in Table 1 as a whole.

material Public rate (%) Thickness (㎛) Breaking strength (kg / cm 3) Elongation at Break (%) Example 1 Polyethylene 36 8 739 161 Example 2 Polyethylene 37 9 1185 156 Example 3 Polyethylene 35 10 1300 164 Example 4 Polyethylene 30 12 1409 170 Example 5 Polyethylene 39 15 1179 137 Example 6 Polypropylene 36 8 1650 139 Example 7 Polypropylene 36 16 1946 127

Charge / discharge characteristic evaluation

The battery manufactured as described above was subjected to a charge / discharge test to evaluate the characteristics of the battery. A charge-discharge test of the cell was performed by operating a potential-constant current device. Charge and discharge were performed using the constant current and constant voltage method.

First, each cell was charged with a constant current of 200 mA. When the voltage in the closed circuit was 4.2 V, the constant current charge changed to constant voltage layer charge. Subsequently, constant voltage charging was continued. Charging finished 9 hours after the start of charging operation. Subsequently, discharge was performed at a constant current of 200 mA. When the voltage of the closed circuit rose to 3.0 V, the discharge was completed.

Charge and discharge of each battery were detected. In addition, the charge and discharge efficiency and energy density of each battery were calculated.

The detected charge capacity, discharge capacity, charge and discharge efficiency and energy density of each battery according to Examples 1 to 7 and Comparative Example 1 of the present invention are shown in Table 2.

Initial charge capacity (mAh / g) Initial discharge capacity (mAh / g) Charge and discharge efficiency (%) Energy density (Wh / l) Example 1 710 611 86 332 Example 2 709 608 86 331 Example 3 711 606 85 330 Example 4 708 609 86 331 Example 5 710 606 85 330 Example 6 497 352 71 189 Example 7 512 355 69 191 Comparative Example 1 1503 349 23 187

As can be seen from Table 2, the battery according to Examples 1 to 7 was excellent in all of the charge capacity, discharge capacity, charge and discharge efficiency and energy density. Thus, the planned excellent characteristics were realized. The properties of each battery according to Examples 1 to 5, including the polyethylene separator, were particularly excellent.

On the other hand, the battery according to Comparative Example 1 had some short circuit during charging. That is, satisfactory battery characteristics were not obtained.

Evaluation of the safety of the sample cell

The shutdown start temperature of each separator according to Examples 1 to 7 and Comparative Example 1 and the maximum surface temperature of each cell when the cells were externally shorted were investigated.

The shutdown temperature was measured by heating the cell at a rate of rise of 5 ° C. per minute. When 1 kHz was added to increase the AC resistance by two or more digits, the temperature of each battery was measured.

When the battery was externally shorted, the surface temperature of the realized battery was measured to charge the battery under the same conditions as the charge / discharge test. The cell was then heated to 60 ° C. In this state, the maximum temperature of the battery realized when the terminal was shorted by a 12 mV register was measured by a thermocouple.

Table 3 shows the temperature and shutdown temperature of the surface of each battery according to Examples 1 to 7 and Comparative Example 1 realized when an external short circuit occurred.

Shutdown Start Temperature (℃) Temperature of battery surface when external short circuit occurs (℃) Example 1 126 118 Example 2 126 119 Example 3 125 117 Example 4 126 118 Example 5 123 116 Example 6 163 161 Example 7 165 165 Comparative Example 1 - More than 200

As can be seen from Table 3, the shutdown temperature of each cell comprising the separator made of polyethylene according to Examples 1 to 5 ranges from 100 ° C to 160 ° C. The relationship between the temperature of the battery according to Example 1 and the impedance of the battery is shown in FIG. 15. As can be seen from FIG. 15, the impedance of the battery rapidly increased when the temperature of the battery was about 126 ° C.

Each cell containing the separator made of polypropylene according to Examples 6 and 7 was shut down even at a temperature of 160 ° C or higher. The relationship between the temperature of the battery according to Example 6 and the impedance of the battery is shown in FIG. 16. As can be seen from FIG. 16, the impedance of the battery rapidly increased when the temperature of the battery was about 163 ° C.

When the rechargeable batteries were externally shorted, the surface temperature of each battery according to Examples 1 to 5 was 120 ° C. or lower. Thus, the heat generation that occurs when the battery is misoperated is effectively prevented. Therefore, the safety of the battery was preserved. On the other hand, the surface temperature of each battery according to Examples 6 and 7 rose to 160 ° C when the rechargeable battery was externally shorted. Therefore, a lot of heat generation occurs when a battery is used incorrectly. The battery according to Examples 1 to 7, which experienced a shutdown effect when the rechargeable battery was shorted externally, had no smoke inside.

On the other hand, the battery according to Comparative Example 1 had no shutdown effect when the temperature of the battery rose to 180 ℃. When the rechargeable battery was externally shorted, the temperature of the battery surface rose to 200 ° C. In addition, smoke was generated from inside the battery.

Description of the physical characteristics of the separator

The relationship between the breaking strength and the breaking elongation of the separator of each battery according to Examples 1 to 7 is shown in FIG. 17. As can be seen from FIG. 17, as a result of evaluation of the characteristics of the battery, the breaking strength of the separator of each battery according to Examples 1 to 5 was less than 1650 kg / cm 2, thereby obtaining excellent characteristics of the battery. Moreover, breaking elongation is 135% or more. The above mechanical strength has been realized.

It was confirmed that each separator having the mechanical strength had a fibril structure as shown in FIG. 6. An electron microscope photograph at 50,000 times magnification of the separator according to Example 6 is shown in FIG. 18. 6 and 18, it can be seen that the mechanical strength of the separator is related to its microstructure. In order to realize the above mechanical strength, the microstructure of the separator must be a fibril structure.

As a result, the use of a porous polyolefin separator having a shutdown effect when the thickness ranges from 5 μm to 15 μm, the porosity ranges from 25% to 60%, and the temperature of the cell is between 100 ° C. and 160 ° C. results in a high energy density of the cell. And both safety can be obtained.

The use of a porous polyolefin membrane having a thickness in the range of 5 μm to 15 μm, a porosity in the range of 25% to 60%, a breaking strength of less than 1650 kg / cm 2 and an elongation at break of at least 135% ensures both high energy density and safety. It was found that a battery could be obtained.

Second embodiment

In carrying out Examples 8 and 9 and Comparative Example 2, a battery was prepared using the separator according to the second embodiment and its properties were evaluated.

Example 8

A positive electrode was prepared by mixing 95 wt% of LiCoO ₂ used as the positive electrode active material, 2 wt% of graphite used as the conductive material, and 3 wt% of polyvinylidene fluoride. Thus, a positive electrode mixture was produced. N-methyl pyrrolidone was then added in an amount of 0.6 times the positive electrode mixture to prepare a slurry.

Next, the obtained slurry was uniformly applied to one of the aluminum foils to be formed of the positive electrode current collector by the doctor blade method. The aluminum foil was then dried at high temperature to remove N-methyl pyrrolidone. Thus, a positive electrode active material layer was produced. Finally, the press process was carried out by adding to a suitable polyethylene using a roll press. Then, the sample was cut into a size of 300 mm X 50 mm to prepare a positive electrode. A columnar aluminum piece was spot welded to the anode to form the anode terminal.

To prepare the negative electrode, a negative electrode mixture was prepared by mixing 91% by weight of graphite used as the negative electrode active material and 9% by weight of polyvinylidene fluoride used as the binder. N-methyl pyrrolidone was then added in an amount of 1.1 times the negative electrode mixture to prepare a slurry.

Subsequently, the obtained slurry was uniformly applied to one of the copper foils to be formed of the negative electrode current collector by the doctor blade method. The copper foil was then dried to remove N-methyl pyrrolidone to form a negative electrode active material layer. Finally, the press process was carried out by adding to a suitable polyethylene using a roll press. Then, the sample was cut into a size of 370 mm x 52 mm to prepare a negative electrode. The copper rod was spot welded to the cathode to form a cathode terminal.

Meanwhile, 6.7% by weight polyvinylidene fluoride, 9.2% by weight ethylene carbonate, 11.6% by weight propylene carbonate, 2.3% by weight γ-butylolactone, 6.67% by weight dimethyl carbonate and 3.5% by weight LiPF ₆ Mixed with each other. Thus, a polymer electrolyte solution was prepared. Note that dimethyl carbonate serves as a solvent for dissolving polyvinylidene fluoride.

The polymer electrolyte solution obtained as a liquid state was applied to the surface of each of the positive electrode and the negative electrode by the doctor blade method. The positive and negative electrodes were then dried for 3 minutes in a constant temperature tank set at 35 ° C. At this time, dimethyl carbonate did not remain in the polymer electrolyte. The application process was performed such that the polymer electrolyte thickness on each of the positive and negative electrodes was 10 μm.

The separator was composed of a composite material of polyethylene and polypropylene and was a separator having a thickness of 10 μm. The polyethylene to polypropylene ratio in the composite material was 1: 1. A separator composed of a composite material was prepared as follows.

First, 20% by weight of ultra high molecular weight polyethylene (UHMWPE) having an average molecular weight Mw of 2.5 X 10 ⁶ , 30% by weight of high density polyethylene (HDPE) having an average molecular weight Mw of 3.5 X 10 ⁵ and a polypropylene having an average molecular weight Mw of 5.1 X 10 ⁵ 100 parts by weight of a polyolefin mixture comprising 50% by weight was added to 0.375 parts by weight of an oxidation inhibitor to prepare a polyolefin composition.

Then 30 parts by weight of the polyolefin composition was introduced into a twin screw extruder (58 mm diameter, L / D = 42, strong kneading type). In addition, 70 parts by weight of liquid paraffin were fed through the side feeder of the twin screw extruder to melt and kneaded at 200 rpm. Thus, polyolefin solution was prepared in the extruder.

The polyolefin solution was then extruded from a T-die dispersed at the tip of the extruder at 190 ° C. and wound around a cooling roll. Thus, the gel sheet was molded. Subsequently, the gel sheet was simultaneously biaxially stretched at 115 ° C. to obtain a 5 × 5 stretched film. The resulting stretched film was washed with methylene chloride and liquid paraffin was removed. The stretched film was then dried and heat treated. Thus, a microporous separator composed of a composite material of polyethylene and polypropylene was obtained.

The strip-shaped positive electrode and negative electrode having the gel electrolyte layer thus obtained were laminated through a separator to form a laminate. Next, the laminate was wound up in the longitudinal direction. Thus, a 36 mm x 52 mm x 5 mm wound electrode was obtained.

Then, the wound electrode was inserted between the outer film composed of the waterproof multilayer film having a thickness of 100 m. Then, the circumference | surroundings of the exterior film were sealed by heat welding under reduced pressure. Therefore, the wound electrode was hermetically sealed in the outer film. At this time, the positive terminal and the negative terminal were inserted into the sealing portion of the outer film.

Example 9

In this embodiment, the same procedure as in Example 8 was performed except that a separator obtained by attaching a polyethylene separator having a thickness of 5 μm and a polypropylene separator having a thickness of 5 μm to each other was used. Thus, a battery was produced.

Comparative Example 2

In the present Example was carried out in the same manner as in Example 8 except that the polyethylene separator having a thickness of 10 ㎛ are used. Thus, a battery was produced.

The battery thus prepared was charged and discharged several times. In the discharged state, the cell was introduced into a constant temperature tank. The temperature was raised at a rate of 5 ° C. per minute to 140 ° C., 145 ° C., 150 ° C., 155 ° C., 160 ° C., 165 ° C. and 170 ° C., while measuring the resistance at 1 kHz. Each temperature was then maintained for 30 minutes. When the resistance did not decrease while the predetermined temperature was maintained, it was determined that no short circuit occurred. When the resistance decreased, it was determined that a short circuit occurred.

The results are shown in Table 4.

Example 8 Example 9 Comparative Example 2 140 ℃ O O O 145 ℃ O O O 150 ℃ O O X 155 ℃ O O X 160 ℃ O O X 165 ℃ O O X 170 ℃ X X X

The batteries according to Examples 8 and 9 included a separator composed of polyethylene and polypropylene, and a separator formed by adhering the polyethylene separator and the polypropylene separator to each other. Compared with the battery including the separator composed only of polyethylene according to Comparative Example 2, the meltdown temperature was further increased by about 15 ° C. Cells containing a separator with a high meltdown temperature could increase the temperature at which an internal short circuit begins due to the meltdown. Therefore, when the temperature of the battery rose, the occurrence of internal short circuit did not occur easily as compared with the polyethylene separator. Therefore, heat generation resulting from internal short circuit can be prevented.                     

The battery prepared as described above was charged and discharged several times. Then, the battery in the overcharged state of 4.4 V was introduced into the hot tank. While measuring the resistance at 1 kHz, the temperature was raised to 135 ° C, 140 ° C, 145 ° C, 150 ° C and 155 ° C at a rate of 5 ° C per minute. Each temperature was maintained for 30 minutes. If the resistance did not decrease while maintaining at the predetermined temperature, it was determined that no short circuit occurred. When the resistance decreased, it was determined that a short circuit occurred. Since the voltage above 4.4 V, heat often occurred due to a short circuit. Therefore, the measurement was completed when it was confirmed that the resistance was reduced.

The results are shown in Table 5.

Example 8 Example 9 Comparative Example 2 135 ℃ O O O 140 ℃ O O X 145 ℃ O O X 150 ℃ X O X 155 ℃ X X X

The cells according to Examples 8 and 9, including a separator composed of a composite material of polyethylene and polypropylene, and a separator formed by adhering the polyethylene separator and the polypropylene separator to each other, even in an abnormal state overcharged to 4.4 V Compared with the battery according to the meltdown temperature could be increased by more than 15 ℃. The cell according to Comparative Example 2 included a separator composed only of polyethylene. Cells containing separators with high meltdown temperatures could raise the temperature at which internal short circuits begin due to meltdown. When the temperature of the battery rises, internal short circuits did not occur more easily than in the polyethylene separator. Therefore, the heat generation of the battery due to the internal short circuit can be prevented.

In the present invention, a separator formed by attaching a separator composed of a porous polyolefin membrane, a separator composed of a composite material of polyethylene and polypropylene, or a first separator composed of polyethylene and a second separator composed of polypropylene to each other, the above-described mechanical properties and Thermal properties were used. Thus, an increase in energy density and an improvement in safety can be realized unlike the prior art. Therefore, a high performance solid state battery excellent in characteristics and safety as a battery can be realized.

Although the present invention has been described in particular detail in the preferred form and structure, the disclosure of the preferred form of the invention in combination and arrangement of detail and structure of the structure without departing from the spirit and scope of the invention as set forth in the claims below. Can be changed.

The battery of the present invention includes a separator composed of a porous polyolefin membrane, a separator composed of a composite material of polyethylene and polypropylene, or a separator formed by adhering a first separator composed of polyethylene and a second separator composed of polypropylene to each other. Compared to the energy density and safety.

Claims (38)

anode, A cathode disposed to face the anode, A separator disposed between the positive electrode and the negative electrode, and A solid electrolyte existing between the positive electrode and the separator, and between the separator and the negative electrode, The solid electrolyte comprises a mixture of polymer and swelling solvent in a ratio of 1: 5 to 1:10, The separator is made of a polyolefin porous membrane having a thickness in the range of 5 μm to 15 μm and a porosity in the range of 25% to 60%, and the solid electrolyte when the temperature of the solid electrolyte cell is in the range of 100 ° C. to 160 ° C. The impedance of the battery is higher than at room temperature, The solid electrolyte battery, characterized in that the thickness of 5 ㎛ to 19 ㎛. The solid electrolyte cell according to claim 1, wherein the porous polyolefin membrane contains polyethylene. delete The solid electrolyte battery according to claim 1, wherein the electrode comprises a cathode in which lithium ions are used as the electrode reactive species and a cathode in which a carbon material is used. The solid electrolyte cell according to claim 1, wherein the solid electrolyte is a gel electrolyte containing ethylene carbonate, propylene carbonate and LiPF ₆ . The solid electrolyte cell according to claim 5, wherein the solid electrolyte is a gel electrolyte further containing vinylene carbonate and / or 2,4-difluoroanisole. The solid electrolyte cell according to claim 6, wherein the content of each of vinylene carbonate and 2,4-difluoroanisole is 5 wt% or less of the total weight of the solid electrolyte. 8. A solid electrolyte cell according to claim 7, wherein a gel electrolyte comprising polyvinylidene fluoride or a copolymer of vinylidene fluoride is used. The solid electrolyte cell according to claim 8, wherein a copolymer containing vinylidene fluoride and hexafluoropropylene is used. 10. The solid electrolyte cell of Claim 9, wherein the gel electrolyte comprises a copolymer made of vinylidene fluoride and hexafluoropropylene contained in an amount of less than 8% by weight. anode, A cathode disposed to face the anode, A separator disposed between the positive electrode and the negative electrode, and A solid electrolyte existing between the positive electrode and the separator, and between the separator and the negative electrode, The separator is made of a polyolefin porous membrane having a thickness in the range of 5 μm to 15 μm, porosity in the range of 25% to 60%, breaking strength of at least 739 kg / cm 2 and less than 1650 kg / cm 2, and breaking elongation of 135%. Solid electrolyte battery, characterized in that from about 170%. The solid electrolyte cell according to claim 11, wherein the porous polyolefin membrane contains polyethylene. The solid electrolyte cell according to claim 11, wherein the solid electrolyte is a gel electrolyte containing a swelling solvent. 12. The solid electrolyte cell according to claim 11, wherein the electrode comprises a cathode in which lithium ions are used as the electrode reactive species and a cathode in which a carbon material is used. The solid electrolyte cell according to claim 13, wherein the solid electrolyte is a gel electrolyte containing ethylene carbonate, propylene carbonate and LiPF ₆ . The solid electrolyte cell according to claim 15, wherein the solid electrolyte is a gel electrolyte further containing vinylene carbonate and / or 2,4-difluoroanisole. 17. The solid electrolyte cell according to claim 16, wherein the content of each of vinylene carbonate and 2,4-difluoroanisole is 5 wt% or less of the total weight of the solid electrolyte. 18. The solid electrolyte cell according to claim 17, wherein a gel electrolyte comprising polyvinylidene fluoride or a copolymer of vinylidene fluoride is used. 19. The solid electrolyte cell according to claim 18, wherein a copolymer containing vinylidene fluoride and hexafluoropropylene is used. 20. The solid electrolyte cell of Claim 19, wherein the gel electrolyte comprises a copolymer made of vinylidene fluoride and hexafluoropropylene contained in an amount of less than 8% by weight. anode, A cathode disposed to face the anode, A separator disposed between the positive electrode and the negative electrode, and A solid electrolyte existing between the positive electrode and the separator, and between the separator and the negative electrode, The separator is made of a mixed material of polyethylene and polypropylene, the thickness of the porous polyolefin membrane ranges from 5 μm to 15 μm, the shutdown temperature is substantially the same as the shutdown temperature of the separator made of polyethylene, and the meltdown temperature is poly A solid electrolyte battery, characterized in that 10 ℃ to 30 ℃ higher than the meltdown temperature of the separator made of propylene. The solid electrolyte cell according to claim 21, wherein the solid electrolyte is a gel electrolyte containing a swelling solvent. 22. The solid electrolyte cell according to claim 21, wherein the electrode comprises a cathode in which lithium ions are used as the electrode reactive species and a cathode in which a carbon material is used. 23. The solid electrolyte battery of claim 22, wherein the solid electrolyte is a gel electrolyte containing ethylene carbonate, propylene carbonate and LiPF ₆ . The solid electrolyte cell according to claim 24, wherein the solid electrolyte is a gel electrolyte further containing vinylene carbonate and / or 2,4-difluoroanisole. The solid electrolyte cell according to claim 25, wherein the content of each of vinylene carbonate and 2,4-difluoroanisole is 5 wt% or less of the total weight of the solid electrolyte. 27. The solid electrolyte cell according to claim 26, wherein a gel electrolyte comprising polyvinylidene fluoride or a copolymer of vinylidene fluoride is used. 28. The solid electrolyte cell according to claim 27, wherein a copolymer containing vinylidene fluoride and hexafluoropropylene is used. 29. The solid electrolyte cell of claim 28 wherein the gel electrolyte comprises a copolymer made of vinylidene fluoride and hexafluoropropylene contained in an amount of less than 8% by weight. anode, A cathode disposed to face the anode, A separator disposed between the positive electrode and the negative electrode, and A solid electrolyte existing between the positive electrode and the separator, and between the separator and the negative electrode, The separator is formed by adhering a first separator made of polyethylene and a second separator made of polypropylene to each other, the thickness of the separator is in the range of 5 ㎛ to 15 ㎛, the shutdown temperature and the shutdown temperature of the separator made of polyethylene And wherein the meltdown temperature is substantially the same as the meltdown temperature of the separator made of polypropylene. 31. The solid electrolyte cell according to claim 30, wherein the solid electrolyte is a gel electrolyte containing a swelling solvent. 31. The solid electrolyte cell according to claim 30, wherein the electrode comprises a cathode in which lithium ions are used as the electrode reactive species and a cathode in which a carbon material is used. 32. The solid electrolyte cell of claim 31 wherein the solid electrolyte is a gel electrolyte containing ethylene carbonate, propylene carbonate and LiPF ₆ . 34. The solid electrolyte battery of claim 33, wherein the solid electrolyte is a gel electrolyte further containing vinylene carbonate and / or 2,4-difluoroanisole. 35. The solid electrolyte cell according to claim 34, wherein the content of each of vinylene carbonate and 2,4-difluoroanisole is 5 wt% or less of the total weight of the solid electrolyte. 36. The solid electrolyte cell according to claim 35, wherein a gel electrolyte comprising polyvinylidene fluoride or a copolymer of vinylidene fluoride is used. A solid electrolyte cell according to claim 36, wherein a copolymer containing vinylidene fluoride and hexafluoropropylene is used. 38. The solid electrolyte cell of claim 37, wherein the gel electrolyte comprises a copolymer made of vinylidene fluoride and hexafluoropropylene contained in an amount of less than 8% by weight.

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